1. Field of the Invention
The present invention relates generally to methods and apparatus for occluding vascular punctures. More particularly, the present invention relates to a device which may be introduced through a tissue tract to apply pressure directly over the adventitial surface of a blood vessel wall in the region of the vascular puncture.
Coronary and other vascular catheters are usually introduced to a patient's vasculature by the Seldinger technique. A small gauge needle is introduced through the skin to a target blood vessel, such as the femoral artery in the region of the patient's groin for coronary procedures. The needle forms a puncture through the blood vessel wall at the distal end of a tract through the overlying tissue. A guide wire is then introduced through the needle, and the needle withdrawn over the guide wire. An introducer sheath is next introduced over the guide wire, and the sheath and guide wire are left in place to provide access during subsequent procedure(s). Exemplary procedures include diagnostic procedures such as angiography, ultrasonic imaging, and the like, and interventional procedures, such as angioplasty, atherectomy, stent placement, laser ablation, graft placement, and the like. After the procedures are completed, the catheters, guide wire, and introducer sheath are removed, and it is necessary to close the vascular puncture to provide hemostasis (i.e., stop blood loss) and allow healing.
The most common technique for providing "hemostasis" is to apply pressure on the patient's skin in the region of the tissue tract and vascular puncture. Pressure can be applied manually or through the use of mechanical clamps and other pressure-applying devices. While effective in most cases, the application of external pressure to the patient's skin suffers from a number of disadvantages. When applied manually, the procedure is time-consuming, frequently requiring the presence of a nurse for one-half hour or more. For both manual and mechanical pressure application, the procedure is uncomfortable for the patient and frequently requires the administration of analgesics to be tolerable. Moreover, the application of excessive pressure can sometimes occlude the underlying artery, resulting in ischemia and/or thrombosis. Even after hemostasis has apparently been achieved, the patient must remain still and under observation for hours to assure that the bleeding remains stopped. Renewed bleeding through the tissue tract is not uncommon and can result in hematoma, pseudoaneurisms, and arteriovenous fistulas. Such complications may require blood transfusion, surgical intervention, or other corrective procedures. The risk of these complications increases with the use of larger sheath sizes, which are frequently necessary in interventional procedures, and when the patient is anticoagulated.
To overcome these problems, several groups have proposed the use of bioabsorbable plugs and fasteners to stop bleeding. Generally, these approaches rely on placing a bioabsorbable material, such as collagen, at the adventitial blood vessel wall over the puncture site. While potentially effective, the use of collagen plugs also suffers from certain problems. It can be difficult to properly locate the plug at the interface between the tissue and adventitial surface of the blood vessel. To help in such positioning, some systems rely on placement of a fastener within the blood vessel lumen to locate and anchor the collagen plug. The use of such fasteners, however, can cause other complications, such as thrombosis, embolization, and the like.
A more effective approach has been proposed in co-pending applications Ser. No. 07/989,611; Ser. No. 08/148,089; and PCT/US93/11864. A suture applying device is introduced through the tissue tract with its distal end located at the vascular puncture. One or more needles on the device are used to draw a suture through the blood vessel wall on opposite sides of the puncture, and the suture is secured directly over the adventitial surface of the blood vessel wall to provide highly reliable closure. While a significant improvement over the use of manual pressure, clamps, and collagen plugs, in rare cases there can still be blood leakage through the sutured vascular puncture, particularly when the patient has been heavily treated with anticoagulants. Moreover, it is desirable to be able to tightly cinch the suture loops which are formed to assure complete closure of the puncture.
For these reasons, it would be desirable to provide improved methods and devices for effecting and enhancing hemostasis at vascular puncture sites after vascular catheterization procedures. In particular, it would be desirable to provide improved methods and devices for stopping bleeding at vascular puncture sites which have been sutured as a primary means of closure. It would be further desirable if such methods and devices could also serve as a primary means for effecting hemostasis, without prior suturing or other closure procedures. It would be even further desirable if such methods and devices could also be used for advancing and tightening suture knots which are formed directly over the adventitial surface of the blood vessel wall.
2. Description of the Background Art
A device and method for placing an inflatable balloon over a vascular puncture site and applying laser energy to thermally weld the artery are described in U.S. Pat. No. 4,929,246. Hemostatic closure devices which place a collagen plug and polymer anchor on the adventitial and luminal surfaces of a blood vessel at a puncture site are described in a brochure of the Kensey Nash Corporation entitled The Hemostatic Puncture Close Device (undated). Vessel closure devices employing collagen and other plugs are described in U.S. Pat. Nos. 5,222,974; 5,192,302; 5,108,421; 5,061,274; 5,021,059; 4,890,612; and 4,744,364. A three part hemostasis device for introducing a collagen plug over a vascular puncture site is described in Merino et al., A Vascular Hemostasis Device for Percutaneous Interventional Procedures, Mount Sinai Medical Center, New York, N.Y. (undated) and Ernst et al., Immediate Sealing of Arterial Puncture Sites after Catheterization and PTCA Using a Vascular Hemostasis Device With Collagen: An International Registry, (undated). Knot pushers, appliers, and related suturing devices are described in U.S. Pat. Nos. 5,176,691; 5,201,744; 5,250,054; 4,803,984; 2,595,086; 2,131,321; 1,940,351; and 1,574,362.
Co-pending applications having Ser. Nos. 07/989,611, 08/148,089, and PCT/US93/11864, describe methods and apparatus for suturing vascular punctures.